Spring band biased movable contactor for hybrid crash sensor switch

ABSTRACT

A multidirectional sensor for a passive restraint system for a vehicle. The sensor includes a housing and a mass in the form of a disk located in a cavity defined within the housing. The disk is free to move in the cavity from an initial position to one of a number of actuation positions under the influence of a &#39;&#39;&#39;&#39;g&#39;&#39;&#39;&#39; force created in a collision situation. The sensor acts as a switch in an electrical circuit. The switch is open when the disk is in the initial position and closed when the disk is in one of the actuation positions. A spring is secured to the disk to retain the disk in the initial position and resist movement of the disk to one of the actuation positions. The spring is designed and arranged so that, in any direction of movement of the disk, the resultant or composite movement of the spring mass is in the same general direction as the movement of the disk so that the time it takes the disk to move to one actuation position is relatively equivalent to the time it takes the disk to move to any other actuation position. In the preferred embodiment, the spring comprises a thin metal band prestressed to wind upon itself; the band is wound around the periphery of the disk with its free end anchored to the housing so that the disk is normally held against a suitable backing surface by the band. In a collision situation, the disc, during movement to an actuation position, rotates and partially unwinds itself from the band.

United States Patent n91 Kaiser [75] Inventor: Hermann Kaiser, Detroit,Mich.

[73] Assignee: Eaton Corporation, Cleveland, Ohio.

[22] Filed: Dec. 30, 1971 21 Appl. No.: 214,013

[52] US. Cl..... 200/6l.45 R, ZOO/61.48, ZOO/ 61.51,

200/166 BA [51] Int. Cl. H01h 35/14 [58] Field of Search 200/8 A, 11 A,16 C,

200/16 D, 61.45 R, 61.53, 61.44, 61.76,166 BB, 166 BF, 166 BA PrimaryExaminer-J. R. Scott Attorney.lohn W. Yakimow 1 July 31, 1973 [57]ABSTRACT A multidirectional sensor for a passive restraint system for avehicle. The sensor includes a housing and a mass in the form of a disklocated in a cavity defined within the housing. The disk is free to movein the cavity from an initial position to one of a number of actuationpositions under the influence of a g force created in a collisionsituation. The sensor acts as a switch in an electrical circuit; Theswitch is open when the disk is in theinitial position and closedwhenthedisk is in'one of the actuation positions. A spring is secured tothe disk to retain the disk in the initial position and resist movementof the disk to one of the actuation positions. The spring is designedand arranged so that, in any direction of movement of the disk, theresultant or composite movement of the spring mass is in the samegeneral direction as the movement of the disk so that the time it takesthe disk to move to one actuation position is relatively equivalent tothe time it takes the disk to move to any other actuation position, Inthe preferred embodiment, the spring comprises a thin metal bandprestressed to wind upon itself; the band is wound around the peripheryof the disk with its free end anchored to the housing so that the diskis normally held against a suitable backing surface by the band. In acollision situation, the disc, during movement to an actuation position,rotates and partially unwinds itself from the band.

28 Claims, 14 Drawing Figures PATENIEDJUL3 1 ms SHEET l 0F 5 l I mm"Passive restraint devices, such as illustrated in US. Pat. No.3,414,292, are available for use on vehicles. These devices include abag which inflates upon the detection by a sensor of a givendeceleration force which occurs upon collision of the vehicle with anobject. A number of sensors have previously been proposed, e.g., seedisclosures in US Pat. No. 3,485,973 (Kaiser); No. 3,489,9l7.(G urol);No. 3,495,675 (I-Iass et al.); No. 3,552,768 (Kaiser); No. 3,556,5563,571,539 (Kaiser et al.).

The purpose of a crash sensor is to detect when a vehicle has beeninvolved in a collision with another object and to thereupon causeactuation of a device to protect the occupants of the vehicle. Ifvehicles were involved in purely head on collisions, the problemsincurred in designing a crash sensor would be greatly reduced. Sincethis is not the case, it is desirable to have a crash sensor which willoperate in a given manner over a large angular range with a highdegreeof confidence. The angular forces which tend to cause a crash sensor toactuate also create secondary forces on certain components, such asthespring, of certain sensors which cause these components to move .in amanner to resist actuation.-ln order to develop a highly reliablesystem, it is necessary to remove these undesirable secondary forces onthe components of a sensor.

BRIEF SUMMARY OF THE INVENTION According to an important feature of thepresent invention, these undesirable secondary forces have beeneliminated by providing a spring connected to and movable with a disklocated in a cavity defined in a housing. The disk is normally situatedat an initial position in the cavity and isadapted to move to one of anumber of actuation positions upon a change of velocity of the housing.The spring is normally operative to resist movement of the disk from theinitial position. During a change of velocity of the housing, theresultant movement of the mass of the spring is in the same generaldirection as the movement of the mass of the disk from the initialposition to anyone of the actuation positions. Since the collisionforces act on the spring in the same general manner as the collisionforces act on the disk, the effect of the movement of the mass of thespring is additive to the movement of the mass or the disk so that thereare no secondary forces acting in a manner to resist actuation.

(Goetz and No.-

coiled metal band prestressed to wind upon itself, e.g.,

a Negator spring manufactured by Hunter Spring, a Division of AmetexInc. One endofthe spring is wound around the disk and the other end isconnected to an electrical contact at the junctionof the angular sides.The contact includes a plurality of electrically conduc-I tive'fin gers.In operation, the described disk-springcontact arrangement becomes anelectrical switch which is actuated by the g force that exists during acollision. The exertion of a given g'" force for a given period of timecauses the disk to move outward against the force exerted by the bandinto contact with the fingets and thereby complete an electric circuit,(#i.e., the

BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is a schematic view of a sensorlocated in an electrical circuit.

FIG. 2 is a perspective view of a sensoraccording to the invention withthe sensor cover-removed for clarity. FIG. 3 is a sectional view takenon line 3-3 of FIG. 2, and including the sensor cover. 1

FIG. 4 is a top plan view with the" sensor cover removed illustratinganother sensor embodying features of the disclosure. I i A j a FIG. 5 isa sectional view taken on line 5-5 of FIG. 4, and including the sensorcover. FIG. 6 is a top plan view, with the sensor cover removed,illustrating still another sensor embodying features of the disclosure.

FIG. 7 is a sectional view taken on line 7 7 of FIG.

- 6, and including the sensor cover.

FIG. 8is a fragmentary front view of a contact use in the embodimentillustrated in FIG. 6.

FIG 9 schematically illustrates an arrangement for wiring the embodimentillustrated in FIG; 6.

FIG. 10 schematically illustrates another' arrangement for wiring theembodimentillustrated in FIG. 6. FIG. 11 is a top plan view, withthesensor cover removed, of yet another sensor embodying features of thedisclosure.

According to a further feature of .the invention, the

spring comprises an elongated member having arelatively-coiledconfiguration and is prestressed to move toward one ofits configurations. The spring member is arranged to move toward itsprestressed configuration to normally urge the disk to'the initial diskposition, and is arranged to move away from its prestressedconfiguration to yieldablyallow movements of the disk toward any one ofthe disk actuation positions upon a change of velocity of the housing.

According to one of the disclosed embodiments, the disk is positioned ina narrow cavity having apair of angular sides defining therebetween theinitial position and a curved contact defining the plurality ofactuation positions. The disk is held against the angular sides .of thecavity by a compact, resilient device such as a F1612 is a sectionalview taken on line 'l2l2of FIG. 11, and including the sensor cover.

FIG. 13 is a top pla'nview, with 'the'top portions removed, of stillanother sensorembodying featuresof the disclosure. 5 f v I J FIG. 14 isa fragmentary sectional view taken on line 14-14 of FIG..13, and.including the sensor top portions;

DETAILED DESCRIPTION OF THE DRAWINGS FIG." 1 schematically illustratesan electricalcircuit I 12 that is used in a passive restraint system ofa known design for a vehicle, e .g., the system illustrated in US.

cal power source 16 illustrated as a battery and one lead 18 of a sensor20. A second lead 22 of sensor is connected to power source 16. Whensensor 20 isactuated by a collision condition, it acts as a switchcompleting a circuit between actuator 14 and power source 16. Thecompletion of the circuit causes the passive restraint system tooperate.

One embodiment of a sensor according to the present disclosure isillustrated in FIGS. 2 and 3 and is generally indicated at 24. Sensor 24includes a generally cupshaped housing 26 having an electricallynonconductive plate 28 with a relatively flat sliding surface 30 andangularly related, relative to each other, guide or side walls 32 and34. A suitable cover 36 is provided for housing 26 having anelectrically nonconductive plate 38 with a relatively flat surface 40parallel to surface 30. Walls 32 and 34 intersect at an angle of 90which may be on opposite sides of the forward direction A in which thesensor 24 would normally be moving in a vehicle.

A cylindrical disk 42 is resiliently held at the intersection of walls32 and 34 at an initial position by a band spring 44 such as a Negatorspring. Spring 44 is a tightly wound metal band which when free windsupon itself into a coil about one or both ends. If spring 44 has aconstant width throughout its length it will be a constant force device.It should be appreciated that a band spring is a very low mass device bydesign. Spring 44 is wound around disk 42 between upper and lower lips46 and 48 at one end and is secured at its other end to a contact 50mounted in housing 26. A lead 51 comparable to lead 18 in FIG. 1 isconnected to contact 50 and extends outwardly from housing 26.

In instances where contact 50 is located away from wall 34 asillustrated in FIGS. 2 and 3, wall 32 may be made upof an upper and alower section 52 and 54 (FIG. 3) having lower and upper surfaces 53 and55, respectively, spaced a given amount to allow spring 44 to passtherebetween during movement of disk 42 and prevent vertical oscillationof the spring.

An arcuate, electrically conductive, resilient contact 56 is locatedbetween walls 32 and 34 distal from the walls intersection. Contact 56includes a plurality of movably spaced fingers 58 which locate aplurality of actuation positions. The fingers 56 are connected to aconductive bar 57 which is connected to a lead 59, comparable to lead 22in FIG. 1, which extends outwardly from housing 26.

During a head on collision, a vehicle, and accordingly a sensor 24mounted thereon, will decelerate. The deceleration is not at a constantrate. As parts of the vehicle crush, the vehicle can and does acceleratea slight amount. The overall deceleration exerts a given g force on disk42 causing the disk. to move from the initial position against the forceof spring 44 away from the intersection of walls 32 and 34 toward one ofthe actuation positions at I contact 56. This movement causes disk 42 torotate unwinding it from spring44 and thereby exposing a previouslyunexposed portion of the spring. If the deceleration lasts over asufficiently long period of time, contact will be made between disk 42and fingers 58 pushing the fingers toward wall 60 of cover 36.Preferably, contact is also made between the previously unexposedportion of spring 44 and the fingers 58. In such a way a more positiveelectrical contact can be assured since it is highly unlikely that thepreviously unexposed portion of spring 44 is contaminated by foreignmatter. This contact between the disk and/or spring and the fingers willresult in the closing, through contact lead 51, contact 50, disk 42and/or spring 44, fingers 58, bar 57 andlead 59, of that portion ofelectrical circuit 12 in sensor 24 and the actuation of the passiverestraint system.

During an angular collision the force exerted on disk 42 will have bothforward and sideward components. As long as the collision occurs withinthe angle included between walls 32 and 34, the force resulting from thecollision will cause a closing of the circuit through the sensor. Bytaking into consideration the various factors referred to in US. Pat.No. 3,556,556 a sensor 24 may be designed to complete the circuit oractuate above a given collision speed and at a given angular collision.If desired, the 90 included angle illustrated in FIGS. 2 and 3 may beincreased or decreased;

It should be appreciated that the entire deceleration force acts throughdisk 42 and that portion of spring 44 wound around the disk. The portionof spring 44 between disk 42 and contact 50 has no material affect onthe operation of the sensor ineither a head on" or an angular collision.This is a significant departure from the operation of previous sensors.

FIGS. 4 and 5 illustrate another embodiment of the disclosure in which asensor 62 has two disks 64 and 66 located between upper and lowersurfaces 68 and 70 partially defining a cavity 71 in a housing 72'. Thedisks are biased against a backing surface 74 in housing 72 by theband-type spring 75 previously described which is wound clockwise at oneend around disk 64 between upper and lower lips (not illustrated) andcounterclockwise at the other end around disk 66 between upper and lowerlips 65 and 67 and secured at a center position to a post 76 located atthe midpoint of backing surface 74. Post 76 comprises a screw 78 passingthrough upper and lower washers 80 separated by a bushing 82. A nut 84is used to hold the screw. 78 rigid relative to housing 72. The includedangle defined by backing surface 74 in cavity 71 is greater than 180.

A contact 88 is illustrated as a segment of a circular surfacesymmetrical about post 76 and contacting the outer ends of backingsurface 74. Contact 88 includes an upper and a lower member 90 and 92,respectively, each having a plurality of spaced fingers 94 and 96projecting respectively below and above upper and lower surfaces 68 and70. A cavity 98 is located behind fingers 94 and 96 to allow movement ofthem away from post 76. Referring again to FIG. 1 a lead 18 may beconnected to upper member 90 and a lead 22 tolower member 92. 7 i

In operation, the g force created by deceleration existing in acollision acts against both disks 64 and 66. If the collision is head onboth disks will move simultaneously outward into contact with thefingers 94 and 96 thereby completing the electrical circuit 12 throughcontact 18, fingers 94, disks 64 and 66, fingers 96 and contact 22 toactuate the passive restraint'system. The duration of the contact ismaintained by the fact'that the fingers move rearwardly into cavity 98as the disks 64 and 66 are forced further away from post 76 as a resultofthe deceleration forces. In an angular" collision of, for example, 45degrees clockwise off dead center, as seen in FIG. 4, disk 66 will makecontact with fingers 94 and 96 thereby completing the electricalcircuit'l2 prior to contact between disk 64 and fingers 94 and 96. Thisearly contact of disk 66 is a result of the fact that disk 66 has ashorter distance to travel than disk64. It should be appreciated,however, that the difference in time between contact of disk 64 and disk66 with fingers 94 and 96 is minimal. The presences, therefore, of thetwo disks increases the redundancy of sensor 62.

It should again be noted that the mass of spring 75 has little if anyeffect on the operation of sensor 62 in either a head on or an angularcollision. It should also be noted that contact 88 may be replaced by acontact 56 illustrated in FIGS. 2 and 3 and lead 18 connected to contact56 and lead 22 connected to post 76.

FIGS. 6 to illustrate yet another embodiment of the disclosure in whicha sensor 101 has two sets of disks 100 and 102, each similar to the setillustrated in FIGS. 4 and 5, located in a single housing 104. Set 100comprises disks 106 and 108 biased against a backing surface 110 by aband-type spring 112 in the manner previously described for FIGS. 4 and5. Directly below set 100, set 102 comprises a mating set of disks 1 14and 116, illustrated schematically in FIGS. 9 and 10, which are similarto disks 106 and 108 and biased against a second backing surface 118 byanother band-type spring 120 in the manner previously described.-Aonepiece contact 122 comprising a plurality of upper and lower spacedfingers 123 and 124projecting inwardly toward the disks 106, 108, 114and 116 defines a segment of a circular surface terminating adjacent theouter ends of backing surfaces 110 and 118. The'included angle ofoperation, as illustrated, may be greater 9. 106 108 +114 116 From theabove it can readily be seen that the redundancy of the system isgreatly increased over those of prior systems. Inadvertent actuation isalso reduced.

Sensor 101 may also be wired to leads l8 and 22 in another manner whichis illustrated in FIG. 10. Lead'18 may be connected to contact 122 andlead 22 may be connected to springs 112 and 120. The circuit acrosssensor 101 in such an arrangement will be completed upon engagement ofany one of the disks 106,108, 114

, or 116 with contact 122. This method of wiring also than 180 degrees.A'cavity 126 is located rearwardly of contact 122 to allow movement offingers 123 and 124 away from surfaces 110 and 118 upon contact with thedisks to extend the time duration of contact therebetween.

In operation deceleration forces caused by a'collision will result incorresponding movement of disks 1'06 and 114 and disks 108 and 116. Inthe event ofa head on collision all disks will engage contact 122 at thesame instant. For an angular collision, disks 106 and 114 will engagecontact 122 at the same time and disks 108 and 116 will engage contact122 at an instant before or 7 after disks 106 and 114 make engagementdepending upon what side of center contact is made. The presence ofcavity 126 and movement of the fingers into the cavity will result inthe duration of the engagement being increased over that of a rigidcontact.

The sensor 101 may be wired to leads 18 and 22 in several manners. FIGS.7 and 9 illustrate one method in which lead 18'may be attached tospring112 of set 100 and the other lead 22 may be attached to spring 120of set 102. The sets 100 and 102 may be insulated from one another byany one of a number of known ways. In the embodiment'illustrated inFIGS. 7 and 9, before the circuit through sensor 101 can be completed, adisk 106 or- 108 from set 100 and a disk 114 or 116 from set 102 must beengagedwith contact 122 at the same time. The completion of the circuitthrough sensor 101 could therefore occur when engagement occurs betweenthe disks and the contact in any one of the following combinations. Thenumbers correspond to the disks engaged with contact 122.

OUIJiUNtgreatly increases redundancy over prior systems. Othervariations in wiring, for example, modifications of those previouslydescribed, may also be used.

FIGS. 11 and 12 illustrate another sensor 123 which embodies features ofthe disclosure which are similar to those illustrated in FIGS. 4 to 10.Two disks 124and 126 are located in a recess 128 in a housing 130.Recess 128 is defined by upper and lower surfaces 132 and 134, sidebacking surfaces 136 and 138 interconnected by a rear backing surface140 to define a pair of initial positions 142 conforming to theconfiguration of disks 124 and 126 and a forward parabolic shapedcontact 144. A smaller recess 146 communicates with recess 128.

Each disk, 124, 126, comprise an upper and a lower portion 148 and 150interconnected by a stud 152 upon which is engaged a bushing 154 that isadapted to be rotated. A spring 156 has a coiled portion 158 located inrecess 146 and a pair of outer arms 160 and 162. Each arm 160, 162 hasacircular end portion 164 and 166 respectively, engaged with a busing154. The spring 156 is prestressed to retain disks 124 and 126 withintheir respective initial positions 142 respectively against walls 136and 140 and 138 and 140.

Contact 144 includes separate upper and lower portions 157 and 159 eachhaving a plurality of spaced fingers 161 similar to those'illustrated inFIGS. 4 and 5.

Upper portion 157 is connected to lead 18 while lower portion 159 isconnected to lead 22 in FIG. 1. v

In operation, sensor 123 is mounted on a vehicle which is normally movedin the direction indicated by arrow A. Upon the occurrence of a head oncollision both disks will be forced into engagement with contact 144 atthe same time. During an angular collision, for example, 30 relativetothe direction of arrow A, one disk will move into engagement withcontact 144 while the other disk will maintain its position asillustrated in dot-dash lines in FIG. 11. In either instance, either ahead on or an angular collision, the disks 124 and 126 and spring 156move as a unit. As in' the embodiments previously described, this factoris significant since the force exerted by the collision does not impairthe operation of the sensor. This is a major departure frommultidirectional prior art sensing devices.- When either disk 124 or 126engages contact 144 the circuit defines an outer portion of recess 167and terminates proximate the ends of walls 168 and 170. Fingers 172 areconnected to lead 18 and fingers 173 are connected to lead 22. Tworotatable posts 174 and 176 are located on either side of the initialposition of disk 169 and each includes a drum 178 adapted to be rotatedon a needle roller 180 mounted in housing 165.

A band-type spring 182, i.e., a band prestressed to wind upon itselfinto a coil, is wound at its ends around each of the drums 178 severaltimes. One of the ends is wound in a clockwise direction and the otherend is wound in acounterclockwise direction. Spring 182, in-

termediate its ends, encircles a portion of disk 169 between upper andlower lips 179 and 181.

In operation, as forces are exerted against disk 169, the disk movesalong the lower surface 184 into contact with fingers 172 and 173completing the circuit through sensor 163. Movement of disk 169 isrestrained by the natural tendency of the ends of spring 182 to coilaround drums 178. It will be noted that dur ing a head on collision bothends will unwind evenly. During angular collisions one end will unwindmore than the other end. If the band is a constant width and thicknessit will be a constant force device, i.e., the force will not depend uponthe amount of uncoiling that occurs. In such a case the force exerted ondisk 169 will be the same whether the forces are from a head on or anangular collision. Further, as in the case for the other embodiments ofthe disclosure, the forces exerted upon spring 182 or the othercomponents of the sensor 163 do not affect its actuation.

In all of the above-referred to embodiments certain design factorsshould be considered. The material used to define the backing surfacesshould be of a type which will absorb impacts by the disks withoutcausing a significant rebound. Further, the surfaces on which the disksslide should be smooth and free from protrusions. The distance betweenthe disks and the contact should be chosen so that the disks will notengage the contact inadvertently or during minor collisions or shockssuch as created by an automobile hitting a pot hole" in a road. Also,vertical movement of a disk should be kept-to a minimum. This may beaccomplished by having the distance between the upper and lower wallsten to twenty thousands of an inch greater than the maximum thickness ofa disk. In determining this distance as well as the design of the disksand springs, it is necessary to consider not only the magnitude of the gforce created by the change in velocity but also the duration of the g"force. It should be appreciated that a collision condition involving anautomobile at which the sensor should actuate a passive restraint systemmight have a lower g" exerted when the automobile hits a hole in theroad, however, the duration of the g force created by the collision willbemuch longer than the duration of the g force created by the hole inthe road.

It should also be appreciated that the winding of the spring around thedisks illustrated in FIGS. 4to 8 may be a significant factor. In theillustrated embodiments care must be taken not to permanently deform thespring proximate the center pole or contact. By winding the springs asillustrated in these figures the spring section connected to a firstdisk will prevent the second disk from becoming lodged between the firstdisk and the center pole or contact. It may further be desirable whenusing two disks in a single cavity to construct the force than thatcavity in a manner to provide a separate V-shaped support for each disk.In viewing FIG. 2 it will be readily apparent that the two V-shapedsupports would have side walls 32 and 34.for each of the two disks 42located on a single flat sliding surface 30. A single contact 56 couldbe used in such an arrangement.

It is further contemplated thata single vane in the form of a thin platepivotally connected to a center post could be located between two disksto keep them from interferring with one another. For example, in theembodiment illustrated in FIGS. 4 and S-the thin plate would bepivotally connected to post 76 between disks 64and 66 and would extendto a position proximate I contact 88. The plate could have an edgeinsliding engagement with surface and be slightly narrowerthan thedistance between surfaces 68 and 70. p

In each embodiment the spring-disk(s) relationship is such that thespring moves in the same general direction as the disk(s) from theinitial position to one of the actuation positions. The force exerted onthe mass of the spring by the collision, therefore, does not act in amanner which is opposed to theforce exerted on the mass of .the disk.The effect of the disclosed springdisk(s) relationship is that themovement of the mass of the spring is additive to the movement of themass of the disk(s). This additive movement eliminates secondary forceson the movable components which would tend to cause the components tomove in a manner to resist actuation.

It should further be appreciated thatthespring in each, of the disclosedembodiments comprises an elongated member having a relatively straightconfiguration and a relatively coiled configuration. The spring isprestressed to move from one configuration to the other configuration tonormally urge a vdisk(s) to the initial position. The presence of aforce created by a collig sion moves the disk(s) from the initialposition .to one of the actuation positions and forces the spring tomove against the prestressed force from one configuration to the otherconfiguration. I

What is claimed is: 1. An apparatus to sense a change in velocity of amoving body, said apparatus comprising: a. means defining an initialposition on said body; b. means defining a plurality of actuationpositions on said body spaced from said initial position and located ina plurality of directions from said initial position; t c. a membermovable between said initial position and said actuation positions inresponse to changes in velocity of said body; I d. a yieldable resilientband holding said movable member and prestressed to wind upon itselfinto a tightly wound coil; and e. means mounting said band l. tonormally urge said movable member to and yieldably hold said movablemember in said initial position in response to self-winding of said bandupon itself, and 2. to allow said band to unwind in response to movementof said movable member to one of said actuation positions during achange in velocity of said body, whereby the unwinding band yieldablyresists the movement of the movable member. 2. An apparatus according toclaim 1 wherein:

ing:

ing:

f. said body includes two connected walls located 'at an angle withrespect to one another and having outer ends;

g. said initial position is located at the connection of a portion ofsaid band is located intermediate said upper and lower portions. r

4. An apparatus according to claim 2 wherein;

k. said band is electrically conductive;

1. an electrically conductive contact is located at said actuationpositions;

in. said band and said contact are adapted to be connected in series toan electrical circuit;

in. a portion of said band is wound around said movable member; and

0. said band engages said contact when said movable member is in one ofsaid actuation positions whereby a path for electrical particles iscreated when said movable member is in one of said actuation positionsthrough said apparatus between said band and said contact.

5. An apparatus according to claim 4 wherein:

p. said contact includes a plurality of resilient fingers adapted to bemoved from a first position to a stressed position.

6. An apparatus according to claim 2 wherein:

i. a contact is located at said actuation positions and includes anupper contact having a plurality of re silient upper fingers and a lowercontact having a plurality of resilient lower fingers, said upper andlower contacts being spaced from one another and being electricallyconductive and adapted to be connected in series to an electricalcircuit, said fingers being movable from an initial position to aposition in which they are stressed; and

v j. said movable member is electrically conductive whereby a path forelectrical particles is created when said movable member is in one ofsaid actuation position through said apparatus between said uppercontact, said movable member and said lower contact.

7. An apparatus according to claim 1 wherein:

f. said mounting means includes first and second drums mounted forrotational movement on said body;

g. said band has a first end wound around said first drum;

h. said bandhas a second end wound around said second drum; and

i.'said band engages said disk intermediate said'first and second ends.1

8. An apparatus according to claim 1 further includf. electrical meansto define an open electrical circuit across said apparatus when saidmovable member is positioned at said initial position and a closedelectrical circuit across said apparatus when said movable member ispositioned at one of said actuation positions.

9. An apparatus" according to claim l'further includf. a second membermovable between said initial position and said actuation positions inresponse to changes in velocity of said body; and

' g. wherein said means further mounts said band to normally urge saidsecond movable member and yieldably hold said second movable member insaid initial position and allow said band to unwindin response tomovement of said second movable member to one of said actuationpositions during change in velocity of said body.

10. An apparatus according to claim 9 wherein:

h. said resilient band has first and second ends, said first end iswoundaround said first movable member in oneclockwise direction and saidsecond end is wound around said second movable member in the otherclockwise direction.

1 1. An apparatus according to claim 9 further including:

h.1 means defining asecond plurality of actuation positions on said bodyspaced from and located adjacent to said first plurality of actuationpositions;

i. means defining a second initial position on said body spaced from andlocated adjacent to said first initial position; i 3 1 j. a third membermovable between said second initial position and said second actuationpositions in response to changes in velocity of said body;

k. a fourth member movable between said second initial position and saidsecond actuation positions in response to changes in velocity of saidbody;

l. a yieldably resilient band holding said third and fourth movablemembers and prestressed to wind upon itself into a coil; and v m. meansmounting said second band 1. to normally urge said third and fourthmovable members to and yieldably hold said third and fourth movablemembers in said second initial position in response to self-winding ofthe second band upon itself, and 2. to allow said band to unwind inresponse to movement of said third and fourth movable members to saidsecond actuation positions duringa change in velocity of said body. I

12. An apparatus according to claim 11 wherein:

n. said first plurality of actuation positions include a firstelectrically conductive contact;

0. said second plurality of actuation positions include a secondelectrically conductive contact connected to said first contact by aconductor; a

p. said first and second movable members and said first resilient bandare electrically conductive;

q. said third and fourth movable members and said second resilient bandare electrically conductive; r. a first electrical lead is attached tosaid first resilient band; and

a second electrical lead is attached to said second resilient bandwhereby movement of either said first or second movable members intoengagement with said first contact together with movement of either saidthird or fourth movable members into engagement with said second contactwill define a path for electrical particles to flow between said firstlead and said second lead. 13. An apparatus according to claim 11wherein: n. said first plurality of actuation positions include a firstelectrically conductive contact;

0. said second plurality of actuation positions include a secondelectrically conductive contact connected to said first contact by aconductor;

p. said movable members and said first and second resilient bands areelectrically conductive;

. a first electrical lead is attached to said first and second resilientbands; and

a second electrical lead is attached to said contacts whereby movementof any movable member into engagement with a respective contact willdefine a path through which electrical particles can flow between saidfirst and second leads.

14. An apparatus according to claim 1 wherein said resilient band has asubstantially constant resisting force.

15. An apparatus for sensing a change of velocity comprising:

a. a housing;

b. a first wall in said housing having a first backing surface and anouter end;

c. a second wall in said housing having a second a plurality ofactuation positions located proximate backing surface and an outer end,said first and second backing surfaces together partially defining acavity in said housing;

and between said outer ends of said first and second walls;

. a first disk located in said cavity and contacting g. resilient meansconnected to said disks to urge each of said disks toward theirrespective surfaces and yieldably resist movement of said disks towardsaid actuation positions.

16. An apparatus according to claim 15 wherein: h. a vane is pivotallyconnected to said housing intermediate said first and second walls, saidvane extending from said point of pivotal connection to a locationadjacent said contact intermediate said first and second disks.

17. An apparatus according to claim 1 5 wherein: h. said resilient meansis a band having first and second ends, said band being prestressed towind upon itself to form a coil, said first end is wound around saidfirst disk and said second end is wound around said second disk and saidband is attached intermediate said first and second ends to said housingat a location intermediate said first and second backing surfaces.

18. An apparatus according to claim 15 wherein: h. said disks areelectrically conductive;

19. An apparatus according to claim 18 wherein: h.

. an electrically conductive contact is located at said actuationpositions; and

. the engagement of one of said disks with said contact creates a pathfor electrical particles to flow through said apparatus between saiddisk and said contact.

. said contact includes a plurality of resilient, spaced fingers, saidfingers being adapted to move when engagement is made by them with oneof said disks to absorb the momentum of said contacting disk andyieldably resist further movement of said disk in the disks projectedpath of travel.

20. An apparatus according to claim 15 wherein:

h. said housing has an upper surface and a lower surface, said upper andlower surfaces being parallel and spaced to define a portion of saidcavity;

i. said disks are adapted to slide on said lower surface; and

j. the distance between said upper and lower surfaces is slightlygreater than the dimension of the corresponding portions of said disksto restrain said disks from moving normal to said upper and lowersurfaces.

21. An apparatus according to claim 15 wherein:

h. said resilient means comprises a coil spring having first and secondarms, said first arm being connected to said first disk and said secondarm being connected to said second disk.

22. An apparatus according to claim 15 wherein said resilient meansyieldably resists movement of said disks with a substantially constantbiasing force.

23. An apparatus to sense a change of velocity comprising:

a. a housing having a cavity;

b. means defining an initial position in said cavity;

c. means defining a plurality of actuation positions in said cavityspaced from said initial position and located in a plurality ofdirections from said initial position;

d. a member of a given mass in said cavity; said member being adapted tomove from said initial position to one of said actuation positions upona change in velocity of said housing; and I e. resilient means connectedto said movable member and normally operative to urge said movablemember to said initial position, said resilient means being arranged sothat, in response to movement of said movable member toward any of saidactuation positions, the resultant movement of the mass of saidresilient means is in the same general direction as the movement of themovable member so that the effect of the mass movement of said resilientmeans is always additive with respect to the effect of the movement ofthe movable member.

24. An apparatus according to claim 23 wherein said resilient meansyieldably resists movement of said movable member from said initialposition to any'of said actuation positions with a substantiallyconstant force.

25. An apparatus to sense a change of velocity comprising:

straight configuration and a relatively coiled configuration and beingprestressed to move toward one of said configurations, said springmember engaging said movable member and being'operative position and 2.to move away from said one configuration toward its other configurationto yieldably allow movement of said movable member toward any velocityof said housing. j v I a v 26. An apparatus according to claim 2SwhereinSaid elongated spring member exerts a substantially constant biasingforce in moving from one of its configurations to the otherconfiguration.

27; An apparatus to sensea change in velocity of a moving body, saidapparatus comprising:

A. means defining an initial position on said body; B. means defining anactuation position on said body spaced from said initial position; 'C. amember movable between saidinitial position and said actuation positionin-response to a change oneof saidactuation positions uponja change in nI in velocity of said body; I

D. a yieldable resilient hand holding said movable member andprestressed to wind upon itself intoa tightly wound coil; and E. meansmounting said band l l. to normally urge saidmovable member to and Itially constant biasing force on said movable member.

yieldably hold said movable member in said ini .tial position inresponse to self-winding ofjsaidf

1. An apparatus to sense a change in velocity of a moving body, saidapparatus comprising: a. means defining an initial position on saidbody; b. means defining a plurality of actuation positions on said bodyspaced from said initial position and located in a plurality ofdirections from said initial position; c. a member movable between saidinitial position and said actuation positions in response to changes invelocity of said body; d. a yieldable resilient band holding saidmovable member and prestressed to wind upon itself into a tightly woundcoil; and e. means mounting said band
 1. to normally urge said movablemember to and yieldably hold said movable member in said initialposition in response to self-winding of said band upon itself, and
 2. toallow said band to unwind in response to movement of said movable memberto one of said actuation positions during a change in velocity of saidbody, whereby the unwinding band yieldably resists the movement of themovable member.
 2. An apparatus according to claim 1 wherein: f. saidbody includes two connected walls located at an angle with respect toone another and having outer ends; g. said initial position is locatedat the connection of said walls; and h. said plurality of actuationpositions are spaced along an arcuate line that terminates adjacent saidouter ends of said walls.
 2. to allow said band to unwind in response tomovement of said movable member to said actuation position during achange in velocity of said body, whereby the unwinding band yieldablyresists the movement of the movable member from said initial position tosaid actuation position.
 2. to allow said band to unwind in response tomovement of said movable member to one of said actuation positionsduring a change in velocity of said body, whereby the unwinding bandyieldably resists the movement of the movable member.
 2. to move awayfrom said one configuration toward its other configuration to yieldablyallow movement of said movable member toward any one of said actuationpositions upon a change in velocity of said housing.
 2. to allow saidband to unwind in response to movement of said third and fourth movablemembers to said second actuation positions during a change in velocityof said body.
 3. An apparatus according to claim 2 wherein: i. one ofsaid connected walls is bifurcated and has an upper and a lower portion;and a portion of said band is located intermediate said upper and lowerportions.
 4. An apparatus according to claim 2 wherein: k. said band iselectrically conductive; l. an electrically conductive contact islocated at said actuation positions; m. said band and said contact areadapted to be connected in series to an electrical circuit; n. a portionof said band is wound around said movable member; and o. said bandengages said contact when said movable member is in one of saidactuation positions whereby a path for electrical particles is createdwhen said movable member is in one of said actuation positions throughsaid apparatus between said band and said contact.
 5. An apparatusaccording to claim 4 wherein: p. said contact includes a plurality ofresilient fingers adapted to be moved from a first position to astressed position.
 6. An apparatus according to claim 2 wherein: i. acontact is located at said actuation positions and includes an uppercontact having a plurality of resilient upper fingers and a lowercontact having a plurality of resilient lower fingers, said upper andlower contacts being spaced from one another and being electricallyconductive and adapted to be connected in series to an electricalcircuit, said fingers being movable from an initial position to aposition in which they are stressed; and j. said movable member iselectrically conductive whereby a path for electrical particles iscreated when said movable member is in one of said actuation positionthrough said apparatus between said upper contact, said movable memberand said lower contAct.
 7. An apparatus according to claim 1 wherein: f.said mounting means includes first and second drums mounted forrotational movement on said body; g. said band has a first end woundaround said first drum; h. said band has a second end wound around saidsecond drum; and i. said band engages said disk intermediate said firstand second ends.
 8. An apparatus according to claim 1 further including:f. electrical means to define an open electrical circuit across saidapparatus when said movable member is positioned at said initialposition and a closed electrical circuit across said apparatus when saidmovable member is positioned at one of said actuation positions.
 9. Anapparatus according to claim 1 further including: f. a second membermovable between said initial position and said actuation positions inresponse to changes in velocity of said body; and g. wherein said meansfurther mounts said band to normally urge said second movable member andyieldably hold said second movable member in said initial position andallow said band to unwind in response to movement of said second movablemember to one of said actuation positions during a change in velocity ofsaid body.
 10. An apparatus according to claim 9 wherein: h. saidresilient band has first and second ends, said first end is wound aroundsaid first movable member in one clockwise direction and said second endis wound around said second movable member in the other clockwisedirection.
 11. An apparatus according to claim 9 further including: h.means defining a second plurality of actuation positions on said bodyspaced from and located adjacent to said first plurality of actuationpositions; i. means defining a second initial position on said bodyspaced from and located adjacent to said first initial position; j. athird member movable between said second initial position and saidsecond actuation positions in response to changes in velocity of saidbody; k. a fourth member movable between said second initial positionand said second actuation positions in response to changes in velocityof said body; l. a yieldably resilient band holding said third andfourth movable members and prestressed to wind upon itself into a coil;and m. means mounting said second band
 12. An apparatus according toclaim 11 wherein: n. said first plurality of actuation positions includea first electrically conductive contact; o. said second plurality ofactuation positions include a second electrically conductive contactconnected to said first contact by a conductor; p. said first and secondmovable members and said first resilient band are electricallyconductive; q. said third and fourth movable members and said secondresilient band are electrically conductive; r. a first electrical leadis attached to said first resilient band; and s. a second electricallead is attached to said second resilient band whereby movement ofeither said first or second movable members into engagement with saidfirst contact together with movement of either said third or fourthmovable members into engagement with said second contact will define apath for electrical particles to flow between said first lead and saidsecond lead.
 13. An apparatus according to claim 11 wherein: n. saidfirst plurality of actuation positions include a first electricallyconductive contact; o. said second plurality of actuation positionsinclude a second electrically conductive contact connected to said firstcontact by a conductOr; p. said movable members and said first andsecond resilient bands are electrically conductive; q. a firstelectrical lead is attached to said first and second resilient bands;and r. a second electrical lead is attached to said contacts wherebymovement of any movable member into engagement with a respective contactwill define a path through which electrical particles can flow betweensaid first and second leads.
 14. An apparatus according to claim 1wherein said resilient band has a substantially constant resistingforce.
 15. An apparatus for sensing a change of velocity comprising: a.a housing; b. a first wall in said housing having a first backingsurface and an outer end; c. a second wall in said housing having asecond backing surface and an outer end, said first and second backingsurfaces together partially defining a cavity in said housing; d. aplurality of actuation positions located proximate and between saidouter ends of said first and second walls; e. a first disk located insaid cavity and contacting said first surface, said first disk beingmovable from said first surface to one of said actuation positions inresponse to a change in velocity of said housing; f. a second disklocated in said cavity and contacting said second surface, said seconddisk being movable from said second surface to one of said actuationpositions in response to a change in velocity of said housing; and g.resilient means connected to said disks to urge each of said diskstoward their respective surfaces and yieldably resist movement of saiddisks toward said actuation positions.
 16. An apparatus according toclaim 15 wherein: h. a vane is pivotally connected to said housingintermediate said first and second walls, said vane extending from saidpoint of pivotal connection to a location adjacent said contactintermediate said first and second disks.
 17. An apparatus according toclaim 15 wherein: h. said resilient means is a band having first andsecond ends, said band being prestressed to wind upon itself to form acoil, said first end is wound around said first disk and said second endis wound around said second disk and said band is attached intermediatesaid first and second ends to said housing at a location intermediatesaid first and second backing surfaces.
 18. An apparatus according toclaim 15 wherein: h. said disks are electrically conductive; i. anelectrically conductive contact is located at said actuation positions;and j. the engagement of one of said disks with said contact creates apath for electrical particles to flow through said apparatus betweensaid disk and said contact.
 19. An apparatus according to claim 18wherein: h. said contact includes a plurality of resilient, spacedfingers, said fingers being adapted to move when engagement is made bythem with one of said disks to absorb the momentum of said contactingdisk and yieldably resist further movement of said disk in the disk''sprojected path of travel.
 20. An apparatus according to claim 15wherein: h. said housing has an upper surface and a lower surface, saidupper and lower surfaces being parallel and spaced to define a portionof said cavity; i. said disks are adapted to slide on said lowersurface; and j. the distance between said upper and lower surfaces isslightly greater than the dimension of the corresponding portions ofsaid disks to restrain said disks from moving normal to said upper andlower surfaces.
 21. An apparatus according to claim 15 wherein: h. saidresilient means comprises a coil spring having first and second arms,said first arm being connected to said first disk and said second armbeing connected to said second disk.
 22. An apparatus according to claim15 wherein said resilient means yieldably resists movement of said diskswith a substantially constant biasing force.
 23. An apparatus to sense achange of velocity comprising: a. a hOusing having a cavity; b. meansdefining an initial position in said cavity; c. means defining aplurality of actuation positions in said cavity spaced from said initialposition and located in a plurality of directions from said initialposition; d. a member of a given mass in said cavity; said member beingadapted to move from said initial position to one of said actuationpositions upon a change in velocity of said housing; and e. resilientmeans connected to said movable member and normally operative to urgesaid movable member to said initial position, said resilient means beingarranged so that, in response to movement of said movable member towardany of said actuation positions, the resultant movement of the mass ofsaid resilient means is in the same general direction as the movement ofthe movable member so that the effect of the mass movement of saidresilient means is always additive with respect to the effect of themovement of the movable member.
 24. An apparatus according to claim 23wherein said resilient means yieldably resists movement of said movablemember from said initial position to any of said actuation positionswith a substantially constant force.
 25. An apparatus to sense a changeof velocity comprising: a. a housing having a cavity; b. means definingan initial position in said cavity; c. means defining a plurality ofactuation positions in said cavity spaced from said initial position andlocated in a plurality of directions from said initial position; d. amember in said cavity adapted to move from said initial position to oneof said actuation positions upon a change in velocity of said housing;and e. an elongated spring member having a relatively straightconfiguration and a relatively coiled configuration and beingprestressed to move toward one of said configurations, said springmember engaging said movable member and being operative
 26. An apparatusaccording to claim 25 wherein said elongated spring member exerts asubstantially constant biasing force in moving from one of itsconfigurations to the other configuration.
 27. An apparatus to sense achange in velocity of a moving body, said apparatus comprising: A. meansdefining an initial position on said body; B. means defining anactuation position on said body spaced from said initial position; C. amember movable between said initial position and said actuation positionin response to a change in velocity of said body; D. a yieldableresilient band holding said movable member and prestressed to wind uponitself into a tightly wound coil; and E. means mounting said band 28.The apparatus of claim 27 wherein said band is of constant width andthickness to provide a substantially constant biasing force on saidmovable member.